1. Field of the Invention
The present invention relates to a wideband antenna, and particularly to a wideband antenna, such as a UWB antenna, capable of being applied to UWB (Ultra Wide Band) communications equipment for next-generation ultrahigh-speed communications.
2. Description of the Related Art
UWBs (Ultra Wide Bands) are wireless and capable of more high-speed communications than optical fiber communications, and is expected as a communications means to replace Bluetooth™ which uses 2.4 GHz band, and wireless LANs, which use existing 5 GHz band (IEEE 802.11a), etc.
UWBs are a communications method, which uses wideband and multiband frequencies from 3.1 GHz to 10.6 GHz, to realize 100 M to 1 G/bps high-speed data communications, which requires hitherto nonexistent wide bands of antennas used therein.
It has been substantially determined that 3-5 GHz band is used in the current first UWB communications. Further, it is desired that 2.3-6 GHz band is covered in the case of its use combined with wireless LANs, etc.
As conventional UWB antennas, there are suggested various antennas, such as an antenna with a home-base-shaped conductor sandwiched between dielectrics, and whose baseball-shaped apex is grounded with a power supply sandwiched therebetween (see JP-A-2005-94437); an improved Sierpinski antenna (see JP-A-2004-343424); an improved patch antenna (see JP-A-2005-94499), etc.
However, no wideband antenna has been able to be realized that is small and thin, but which covers the wide band of 2.3-6 GHz, and which is in a relative bandwidth of 50% or more.